From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
Jan Beulich <jbeulich@suse.com>, Wei Liu <wl@xen.org>
Subject: Re: [PATCH v2] x86/ucode: Refresh raw CPU policy after microcode load
Date: Thu, 4 May 2023 12:47:45 +0200 [thread overview]
Message-ID: <ZFONUdkG2ow9uckX@Air-de-Roger> (raw)
In-Reply-To: <20230504102607.3078223-1-andrew.cooper3@citrix.com>
On Thu, May 04, 2023 at 11:26:07AM +0100, Andrew Cooper wrote:
> Loading microcode can cause new features to appear. This has happened
> routinely since Spectre/Meltdown, and even the presence of new status bits can
> sometimes mean the administrator has no further actions to perform.
>
> Conversely, loading microcode can occasionally cause features to disappear.
> As with livepatching, it is very much the administrators responsibility to
> confirm that a late microcode load is safe on the intended system before
> rolling it out in production.
>
> Refresh the raw CPU policy after late microcode load appears to have done
> something, so xen-cpuid can reflect the updated state of the system.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
I'm not fully sure it's worth calling calculate_raw_cpu_policy() if
updated != nr_cores, as it's possible the current CPU where the policy
is regenerated hasn't been updated.
Thanks, Roger.
next prev parent reply other threads:[~2023-05-04 10:48 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-03 18:58 [PATCH] x86/ucode: Refresh raw CPU policy after microcode load Andrew Cooper
2023-05-04 7:08 ` Jan Beulich
2023-05-04 8:08 ` Andrew Cooper
2023-05-04 8:17 ` Jan Beulich
2023-05-04 10:19 ` Andrew Cooper
2023-05-04 8:22 ` Roger Pau Monné
2023-05-04 9:07 ` Jan Beulich
2023-05-04 9:28 ` Andrew Cooper
2023-05-04 10:26 ` [PATCH v2] " Andrew Cooper
2023-05-04 10:47 ` Roger Pau Monné [this message]
2023-05-04 11:00 ` Andrew Cooper
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